This invention relates to a lithium oxide-based amorphous solid. More particularly, the present invention relates to a lithium oxide-based amorphous solid consisting of a Li.sub.2 O/SiO.sub.2 /ZrO.sub.2 composition forming a high ionic conductive thin film.
Recently, lithium ion conductive solid has drawn an increasing attention. Particularly, the lithium ion conductor has been put to practical use as a solid electrolyte of a lithium battery and as an electrolyte of an electrochromic display. The application of the lithium ion conductor as the solid electrolyte of the lithium battery has made a rapid progress in recent years because demands for a battery having a reduced thickness are increasing with miniaturization of electronic devices, especially reduction of their thickness. The application of the lithium ion conductor as the electrolyte of the electrochromic display contemplates to realize an electrochromic display device in the all solid-state arrangement and to stabilize the device characteristics. It is important for both of these applications that a solid electrolyte which has high ionic conductivity and is stable in the normal atmosphere must be developed. In applying the solid electrolyte to all solid-state electrochemical devices, an electrolyte material must be essentially developed which has high chemical stability between a lithium electrode and the electrolyte.
A solid electrolyte thin film material exhibiting high lithium ion conductivity and a method of producing the same are disclosed in Japanese Patent Laid-Open No. 60669/1982 and the like. However, the material disclosed in the prior art reference was not one that has both of the important properties of being high in lithium ion conductivity and highly stable chemically to a lithium metal. For these reasons, all solid-state batteries and all solid ECD's using these electrolytes involve a drawback that their shelf life as well as cycle life are short due to the reaction of the electrolyte with the electrode.